Among the conventionally-known engine oil level detecting devices are ones wherein a float moves up or down in response to variation in an oil level, one example of which is disclosed in Japanese Patent Application Laid-Open Publication No. 2003-184530.
According to the disclosure of the 2003-184530 publication, a float guide rod extends between upper and lower lids closing the upper and lower ends of an outer cylinder, and a float is mounted on the guide rod so that it moves up or down along the guide rod in response to oil level variation.
If applied to an engine of a type where oil stored in a lower portion of the engine is compulsorily taken up or dipped up to lubricate various component parts of the engine, the disclosed oil level detecting device would present the problem that a surface position of the oil does not stabilize so that it is difficult to accurately detect the oil level using the float.